Recently developed cellular telephone systems can receive and transmit multimedia messages including static images, dynamic images, and music. Such multimedia messages can be transmitted and received via internet by cellular telephones adapted to multimedia messages and can be exchanged between the cellular telephones adapted to multimedia messages.
An example of the configuration of the multimedia message allocation system is shown in FIG. 5.
Referring to FIG. 5, a MMS (Multimedia Messaging Service) 1 forms a nucleus of a multimedia messaging service and controls storage, initiation of reception notification, and transfer of the received multimedia messages. The MMS 1 has a mailbox for each subscriber and holds multimedia messages. A PPG (Push Proxy Gateway) 2 is a device for conducting push transfer by which message information of multimedia messages from the MMS 1 or the like is transferred by initiating the network to the portable terminal 4 of a customer. A SMSC (Short Message Service Center) 3 conducts transmission and reception of short messages to and from the portable terminal 4. The portable terminal 4 is a cellular telephone adapted to multimedia messages. A WAP gateway (Wireless Application Protocol Gateway) 5 is a device for interconnecting the internet connection from the portable terminal 4.
The processing flow during allocation of multimedia messages will be explained below with reference to FIG. 5.
If the MMS 1 receives a multimedia message (MM-message), the MM-message is stored in the mailbox of the subscriber, which is the customer in the mailbox 1a, a reception notification (Notification) to the customer is produced, and transfer thereof is initiated. As a result, the MMS 1 requests a push transfer of reception notification to the PPG 2. The PPG 2 that received this request provides a session establishment request to the SMSC 3 so as to initiate the network. The SMSC 3 that received this request transfers to the portable terminal 4 a message that requests to establish a session to the PPG 2. In this case, the SMSC 3 sends the request to the portable terminal 4 as a short message.
The portable terminal 4 that received the request to establish a session to the PPG 2 establishes a session with respect to the PPG 2. As a result, a state of possible communication is established between the PPG 2 and portable terminal 4, and the PPG 2 sends a reception notification from the MMS 1 to the portable terminal 4. The portable terminal 4 that received the reception notification connects to the WAP gateway 5 and transfers to the WAP gateway 5 the notification response (NotifyResp) that came from the portable terminal 4 to the MMS 1. The WAP gateway 5 that receives the notification response sends the transferred notification response to the MMS 1.
The portable terminal 4 then transfers to the WAP gateway 5 a HTTP request (HTTP GET) to acquire a multimedia message from the MMS 1 with a HTTP (Hypertext Transfer Protocol) which is a simple protocol composed of a request and a response corresponding thereto. The WAP gateway 5 received it sends the transferred HTTP request (HTTP GET) to the MMS 1. The MMS 1 receives the HTTP request (HTTP GET) 1, reads the multimedia message stored in the mailbox of the portable terminal and sends it via the WAP gateway 5 to the portable terminal 4. As a result, the portable terminal 4 can receive the multimedia message for which the notification has been received.
In the PPG 2, the communication with the SMSC 3 is conducted with the communication protocol called SMPP (Short Message Peer-to-Peer), but flow control in the SMPP is not clearly defined and this protocol is considered to be unable to prevent or eliminate the appearance of congestion autonomously as a processing system. The resultant problem is that there is a risk of processing being interrupted or terminated in the SMSC 3 or PPG 2 when congestion has occurred in the SMSC 3 or PPG 2. Flow control support was also considered, but in order to produce the SMSC or PPG supporting the flow control, all the existing devices of those types had to be replaced which was unrealistic from the standpoint of cost.
Accordingly, it is an object of the present invention to provide a station such that even if congestion occurs in a station in which congestion cannot be prevented from occurring or eliminated autonomously, the occurred congestion can be eliminated without additional modifications.